1. Field of the Invention
The present invention relates to a treatment apparatus that converges energy waves, such as ultrasonic waves or shock waves, at one point to treat an object body to be treated (hereinafter referred to as a target section) in the noncontact state.
2. Description of the Related Art
A shock wave lithotrity apparatus is one of such apparatuses. In this apparatus, a piezoelectric transducer is driven by a high voltage pulse signal to converge high energy ultrasonic waves from this transducer at one point so as to generate a shock wave. Then, this shock wave is used to disintegrate a calculus, a cancer cell, etc.
An ultrasonic wave pulse apparatus disclosed in U.S. Pat. No. 4,617,931 (Dory) is a conventional example of the shock wave lithotrity apparatus. In this prior art, besides a shock wave generating transducer, an auxiliary transducer for echography is also installed. The shock wave generating transducer is not driven until the focus of the transducer is adjusted on the target section and it is confirmed that the target section coincides with the focus of the transducer using echography.
However, in this apparatus described above, in a case where an operator erroneously operates the switch for generating a shock wave during positioning even when the focus is not properly on the target section, the transducer would be driven so that a generated shock wave could be directed to areas other than the target section. In other words, according to the prior art, pressing the shock wave generating switch always activates and drives the piezoelectric transducer at a high voltage.
Instead of an ultrasonic wave, a discharge in water or an explosive is also used for generating a shock wave.
A hyperthermia apparatus, another treatment apparatus that uses ultrasonic waves, also has a similar problem. The hyperthermia apparatus could use, rather than a high voltage pulse signal, a medium voltage continuous wave signal to activate the transducer.